a{
    text-decoration: none;
}
.clearFix::after{
    content: "";
    display: block;
    clear: both;
}
header{
    width: 100%;
    background-color: #333;
    height: 30px;
    line-height: 30px;
    color: #fff;
    font-size: 12px;
}
header .headerbox{
    padding: 0 20px;
    box-sizing: border-box;
}
header .headerbox .headerlf{
    float: left;
}
header .headerbox .headerrg{
    float: right;
}
header .headerbox .headerrg a{
    color: #fff;
}

.logo-nav{
    height: 50px;
    line-height: 50px;
    background-color: #eee;
    width: 100%;
    padding: 0 20px;
    box-sizing: border-box;
    overflow: hidden;
    transition: all 0.3s;
}
.logo-nav .logo{
    float: left;
    height: 50px;
}
.logo-nav .logo img{
    height: 50px;
}
.logo-nav nav{
    float: right;
    display: flex;
}
.logo-nav .oncontent{
    position: absolute;
    top: -40px;
    height: 40px;
    width: 40px;
    left: calc(50% - 20px);
}
.logo-nav .oncontent div{
    width: 40px;
    height: 5px;
    background-color: #000;
    margin-bottom: 5px;
}
.logo-nav nav li{
    transition:all 0.3s;
    padding: 0 10px;
    box-sizing: border-box;
    border-right: 1px solid #ccc;
    text-align: center;
}
.logo-nav nav li a{
    color: #000;
}
.logo-nav nav li:last-of-type{
    border-right: none;
}
.logo-nav nav li:hover{
    background-color: #333;
    
}
.logo-nav nav li:hover a{
    color: #fff;
}
.jsbox{
    width: 100%;
    height:50px;
    line-height: 50px;
    background-color: #333;
    color: #fff;
    padding: 0 20px;
    box-sizing: border-box;
    font-size: 20px;
}

.jsbox .teacher{
    float: left;
}
.jsbox .student{
    float: right;
}
.yuyanbox{
    width: 90%;
    height: 85px;
    display: flex;
    margin: 0 auto;
    justify-content: space-between;
    margin-top: 20px;
}
.yuyanbox div{
    width: 215px;
    height: 85px;
    border: 2px solid #ddd;
    text-align: center;
    margin: 0 10px;
    flex: 1 1 auto;
    box-sizing: border-box;
    padding: 20px 0 ;
}
.yuyanbox div span:first-of-type{
    color: #2d78f4;
    font-size: 30px;
    margin-right: 10px;
}
.yuyanbox div span:last-of-type{
    font-size: 16px;
    color: #ccc;
}

.ketang{
    width: 85%;
    margin: 0 auto;
    display: flex;
    text-align: center;
    border-top: 2px  solid #2d78f4;
    box-shadow: 0 0 4px #ccc;
    margin-top: 30px;
}
.ketang .ketangtext{
    flex: 1 1 auto;
    background-color: #eee;

}
.ketang .ketangtext h3{
    font-weight: bold;
    margin-top: 25px;
}
.ketang .ketangtext p{
    font-size: 12px;
    font-style: italic;
    margin-top: 10px;
}
.ketang .ketangxiangqing{
    flex: 4 1 auto;
    display: flex;
    flex-wrap: wrap;
}
.ketang .ketangxiangqing .kemu{
    flex: 1 1 100%;
    display: flex;
}
.ketang .ketangxiangqing .kemu div{
    flex:  1 1 auto;
    border-left: 1px solid #ddd;
    border-bottom: 1px solid #ddd;
    width: 20%;
    font-size: 12px;
    text-align: center;
    line-height: 5rem;
}
.ketang .ketangxiangqing .kemu div:nth-of-type(1){
    font-weight: bold;
}
.ketang .ketangxiangqing .kemu div:nth-of-type(3){
    color: #2d78f4;
    font-size: 20px;
    cursor: pointer;
}
.ketang .ketangxiangqing .kemu .live{
    flex: 3 1 40%;
    font-size: 12px;
}
footer{
    width: 85%;
    display: flex;
    margin: 0 auto;
    text-align: center;
}
footer div{
    width: 25%;
    flex: 1 1 auto;
}
footer .bottomlogo img{
    width:100%;
}
footer .footertext{
    margin-top: 50px;
}
footer .footertext p{
    padding: 0 10px;
}
footer .footertext p a{
    font-size: 12px;
    color: #000;
}
@media screen and (max-width:900px){
    .content{
        height: 450px;
    }
}
@media screen and (max-width:800px){
    .content{
        height: 400px;
    }
}
@media screen and (max-width:700px) {
    .content{
        height: 300px;
    }
    .logo-nav{
        top: 0;
        left: 0;
        display: flex;
        position:relative;
        z-index: 6;
        flex-wrap: wrap;
        padding: 0;
        background-color: #fff;
    }
    .logo-nav .oncontent{
        top: 13px;
        cursor: pointer;
        line-height: 40px;
        text-align: center;
        transition: all 0.3s;
    }
    .logo-nav.active .oncontent{
        position: relative;
       
    }
    .logo-nav.active .oncontent div{
        background: #fff;
    }
    .logo-nav.active{
        background-color: #333;
    }
    .logo-nav .logo{
         width: 100%;
         background-color: #fff;
         padding-left:20px;
    }
    .logo-nav.active .logo {
        padding: 0;
        background-color: #333;
    }
    .logo-nav.active .logo img{
        display:block;
        margin: 0 auto;
        
    }
    .logo-nav.active nav li{
        border-right: none;
    }
    .logo-nav.active nav li a{
        display: inline-block;
        border-bottom: 1px solid #fff;
        box-sizing: border-box;
        width: 300px;
    }
    .logo-nav nav{
        width: 100%;
        flex-wrap: wrap;
        padding:0;
    }
    .logo-nav nav li{
       flex: 1 1 100%;
       background: #333;
    }
    .logo-nav nav li a{
        color: #fff;
    }
    .logo-nav nav li:hover{
        background: #fff;
    }
    .logo-nav nav li:hover a{
        color: black;
    }
    .content .sider li h1{
        top:calc(50% - 100px);
        left:calc(50%);
        transform: translateX(-50%);
        font-size:30px
    }
    .content .sider li p{
        top:calc(50%);
        font-size: 20px;
    }
    .yuyanbox div span{
        display:block;
    }
    .yuyanbox div span:first-child{
        font-size: 20px;
    }
    .yuyanbox div span:last-child{
        font-size: 14px;
    }
    .ketang{
        flex-wrap: wrap;
    }
    .ketang .ketangtext{
        padding-bottom: 20px;
    }
    footer{
        flex-wrap: wrap;
    }
    footer div{
        flex: 1 1 100%;
    }
    footer .footertext{
        margin-top: 0;
        font-size: 20px;
        margin-bottom: 20px;
    }
}
@media screen and (max-width:500px) {
    .content{
        height: 250px;
    }
}

